Pin literal Archera signup URL in frontend archera tests (parity with #1280 Go fix)

[cristim]

Context

PR #1280 addressed a CodeRabbit nit on the Go side by pinning the literal Archera signup URL in TestPrintFinalMessage rather than relying on the archeraSignupURL constant. The same anti-regression rationale applies to the frontend tests in frontend/src/__tests__/archera.test.ts, which currently assert:

expect(link!.href).toBe(ARCHERA_SIGNUP_URL);

If ARCHERA_SIGNUP_URL is changed in frontend/src/archera.ts to a wrong destination (typo, accidental UTM, wrong domain), this test passes because the assertion compares against the same imported constant. The CodeRabbit finding on PR #1280: "Using archeraSignupURL here only proves the message prints whatever the production constant currently contains. It will not catch a regression where the constant changes to the wrong destination."

Acceptance criteria

• In frontend/src/__tests__/archera.test.ts, add or replace at least one assertion per surface (offer modal + education page) with the literal canonical URL (https://www.archera.ai/cudly), so a future const change to a wrong destination is caught.
• Keep the existing ARCHERA_SIGNUP_URL-referencing assertion as well, so the test continues to verify "code uses the exported const" alongside "const has the right value".
• Confirm both partnership disclosures (non-gating + sponsorship — see project_archera_partnership memory) regression tests still pass.

Related

• PR feat(archera): soft-pitch insurance after CLI purchase + update web signup link #1280 (analogous Go-side fix landed there)
• CodeRabbit comment on PR feat(archera): soft-pitch insurance after CLI purchase + update web signup link #1280